The interior of the eye is bathed in a fluid often referred to as “aqueous” or “aqueous humor.” This fluid is constantly being renewed. As additional fluid enters the eye, a corresponding amount of fluid must be drained from the eye to maintain a constant intra-ocular pressure. If the drainage of fluid cannot keep up with the entry of new fluid, the intra-ocular pressure will increase. If that pressure increases too much, the optic nerve will be damaged. This condition is often referred to as “glaucoma.”
One way to relieve intra-ocular pressure is to implant a shunt having a one-way pressure-relief valve. When the intra-ocular pressure exceeds a threshold, the valve opens, and excess fluid drains onto a drainage bed. When the pressure drops sufficiently, the valve closes. This relieves the intra-ocular pressure.
Conventional shunts are designed to lead the fluid to the surrounding tissue. As a result, a capsule eventually forms over the valve and thereby interferes with its operation. This is particularly troublesome for patients who have an artificial cornea, (i.e., a keratoprosthesis).